Thermoelectrically powered portable light source

ABSTRACT

Provided is a portable, thermoelectrically powered device, such as a flashlight or headlamp. The device comprises at least one thermoelectric generator for extracting body heat from a user, the Thermoelectric generator located on and extending through an elongated open ended outer shell, a heat sink in contact with an inner surface of the thermoelectric generator and configured to provide an elongated first cooling channel therethrough, circuitry in electrical communication with the thermoelectric generator, the circuitry comprising a transistor oscillator, a step-up transformer and a decoupling capacitor, the circuitry in electrical communication with a power sink, such that in use, a temperature gradient across the thermoelectric generator is sufficient to result in generation of at least about 25 μW of power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT/IB2014/060634, filedApr. 11, 2014, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present technology is a lighting system that relies onthermoelectricity for power. More specifically, it is a flashlight thatis powered from body heat.

Description of the Related Art

Portable light sources such as head lamps and flashlights rely on apower source that is independent of the grid. Often, these light sourcesare used irregularly, are needed in emergency situations and if poweredby batteries, tend to not work when needed as the batteries have died.Even if rechargeable batteries are used, charged batteries must beavailable when those powering the light source die. As a result,alternative designs have been developed that provide a ready powersource.

Hand crank dynamos have been used both in lights and in portable cellphone rechargers. One such design, called the Sidewinder, is voltageregulated to keep the voltage reasonably stable even if the generatorspeed varies. This Sidewinder also includes a miniature flashlightcapability. There is a white Light Emitting Diode (LED) on the top ofthe unit, and when the hand crank is turned, the generated power caneither be used to recharge a cell phone or to turn on the light. A builtin capacitor stores some charge so the light will continue to glow for acouple of minutes after a thirty second charge. The Preparedness Center(Ukiah, Calif.) markets a solar powered, hand crank powered flashlightand AM/FM radio. Safety Buddy, Inc. (Irvine, Calif.) markets a handcrank AM/FM dynamo radio with a lantern light. Unfortunately, the handcrank devices tend to have a short life span, are difficult to use insituations where the user is trying to focus the light on a specificlocation, for example when trying to unlock a door and they cannot behands free.

It is known that thermoelectric generators such as Peltier modules,working on the Seebeck Principle, can be used to produce electriccurrent. The Seebeck Effect states that electric current is producedwhen two dissimilar metals (such as bismuth and telluride) are joined,and one side of their junction is cooled while the other is heated. Asin U.S. Pat. No. 7,626,114 a thermoelectric power supply convertsthermal energy into a high power output with voltages in the Volt-rangefor powering a microelectronic device and comprises an in-planethermoelectric generator, a cross-plane thermoelectric generator, aninitial energy management assembly, a voltage converter and a finalenergy management assembly.

There exists a need to provide a portable light source that can bepowered thermoelectrically, using thermoelectric generators. This wouldremove the requirement for batteries, toxic chemicals or kinetic energyand would provide a flashlight that does not create any noise orvibrations. An additional goal would be to provide a hands freeflashlight. The power source could similarly be employed for otherportable devices having power requirements that are the same or lowerthan a flashlight.

SUMMARY OF THE INVENTION

The present technology provides a portable, thermoelectrically powereddevice that relies on body heat from the user. In one embodiment, thedevice is a light source. The light source can be hand-held, wrist, arm,foot, leg, waist, head-mounted or otherwise in contact with the user'sbody.

The device is may be switchless and is triggered to turn on simply bythe user's body heat.

In another embodiment, a switch is incorporated as a choice to power thelight source either directly from the circuitry, or from a storagesource such as a supercapacitor or rechargeable battery. In both cases,the storage source would be charged from the energy developed by thebody heat.

In one embodiment, a portable, thermoelectrically powered device isprovided, the device comprising: an at least one thermoelectricgenerator for extracting body heat from a user, the thermoelectricgenerator located on and extending through an elongated outer shell; aheat sink in contact with an inner surface of the thermoelectricgenerator, the heat sink configured to provide an elongated firstcooling channel therethrough terminating at a first end and a second endwith an at least one heat sink first aperture and an least one heat sinksecond aperture; and circuitry in electrical communication with thethermoelectric generator, the circuitry comprising a decouplingcapacitor, a transistor oscillator, a step-up transformer and, thecircuitry in electrical communication with a power sink, such that inuse, a temperature gradient across the thermoelectric generator issufficient to result in generation of at least 25 microwatts of power.

In the portable thermoelectrically powered device, the step-uptransformer may be further defined as an about 25:1 to about a 500:1step-up transformer.

In the portable thermoelectrically powered device, the heat sink mayhave a thermal conductivity of at least about 16 W/mK at 25° C.

In the portable thermoelectrically powered device, the device comprisesthe outer shell, the outer shell having a first end and a second end anda bore therebetween, the first end defining an at least one aperture andthe second end defining an at least one aperture and further comprisesan insulating layer adjacent the outer shell.

In the portable thermoelectrically powered device the heat sink may bealuminum, copper, steel, stainless steel or pyrolytic graphite or adiamond coated substrate.

The portable thermoelectrically powered device may further comprise asecond cooling channel between the heat sink and the outer shell andstruts for supporting the inner cylinder in the outer shell.

In the portable thermoelectrically powered device the power sink may beat least one LED and the device is a light source.

In the portable thermoelectrically powered device the light source maybe a head lamp or a flashlight.

In the portable thermoelectrically powered device, the light source maybe a flashlight.

In the portable thermoelectrically powered device the capacitor may bean about 47 μF capacitor.

In another embodiment, a thermoelectrically powered light is provided,the light comprising: at least one thermoelectric generator forextracting body heat from a user; a first end and a second end, thefirst end and second end defining an at least one first aperture and anat least one second aperture, respectively; a heat sink in contact withan inner surface of the thermoelectric generator and defining anelongated first cooling channel; and circuitry in electricalcommunication with the thermoelectric generator, the circuitrycomprising an a decoupling capacitor, a transistor oscillator, step-uptransformer and the circuitry in electrical communication with an atleast one light emitting diode (LED).

The thermoelectrically powered light may further comprising a bodyincluding an insulating layer and a supporting layer and defining a boreextending between the at least one first and at least one secondapertures; the thermoelectric generator located on and extending throughthe body and the heat sink housed in the bore.

In the thermoelectrically powered light the heat sink may have a thermalconductivity of at least about 16 W/mK at 25° C.

In the thermoelectrically powered light, the heat sink may be analuminum, copper, steel, stainless steel, pyrolytic graphite or diamondcoated inner cylinder.

The thermoelectrically powered light may further comprising a secondcooling channel between the heat sink and the body, and struts forsupporting the heat sink in the body.

In the thermoelectrically powered light the step-up transformer may befurther defined as an about 25:1 to about a 500:1 step-up transformer.

In the thermoelectrically powered light, the capacitor across thethermoelectric generator may be an about 47 (or more) μF capacitor.

In the thermoelectrically powered light, the light may be a headlamp ora flashlight.

A method of providing light is also provided, the method comprising: auser holding or pressing a thermoelectrically powered flashlight or bodylamp against their body such that the body contacts an at least onethermoelectric generator of the flashlight or body light, the flashlightor body lamp comprising: the at least one thermoelectric generator; aheat sink in contact with an inner surface of the thermoelectricgenerator; and circuitry in electrical communication with thethermoelectric generator, the circuitry comprising a capacitor, atransistor oscillator, step-up transformer, the circuitry in electricalcommunication with an at least one LED; the thermoelectric generatorextracting body heat from the user; the heat sink removing body heatfrom the thermoelectric generator; the thermoelectric generatorproducing heat energy; and the circuitry communicating an electriccurrent to the at least one LED, thereby providing a steady or aflashing light.

The method may further comprise storing the heat energy as a charge in acapacitor or battery of the flashlight or body light.

The method may further comprise releasing the charge as the electriccurrent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is medial longitudinal sectional view of the flashlight of thepresent technology.

FIGS. 2A, 2B and 2C are cross sectional views of the technology of FIG.1 taken at line A in FIG. 1.

FIGS. 2D-2G show an alternate embodiment of FIG. 1, with FIG. 2F being across-sectional view taken at line A and FIG. 2G being a perspectiveview of this embodiment.

FIG. 3 is a medial longitudinal view of an alternative embodiment ofFIG. 1.

FIGS. 4A, 4B and 4C are cross sectional views of the technology of FIG.3 taken at line A.

FIG. 5A is a medial longitudinal view of a headlamp of the presenttechnology. FIG. 5B is a cross sectional view of FIG. 5A taken at lineB. FIG. 5C is a perspective view of FIG. 5A.

FIGS. 5A, 5B and 5C show an alternative embodiment of the headlamp ofthe present technology.

FIGS. 6A-6C show a keychain flashlight of the present technology.

FIGS. 7A and 7B show a solid core heat sink for use in the presenttechnology.

FIGS. 8A-8G show an alternative embodiment of the flashlight of thepresent technology. FIGS. 8B, 8C and 8D are cross sectional views takenat line B in FIG. 8A. FIG. 8E is a cross sectional view taken at line Ein FIG. 8A. FIG. 8F is a side view of 572, and FIG. 8G is the same sideview but with a flexible solar cell around on 572.

FIGS. 9A-9C show an alternative embodiment of the headlamp of thepresent technology. FIG. 9A is a medial longitudinal view. FIG. 9B is across sectional view of FIG. 9A taken at line B. FIG. 9C is aperspective view of FIG. 9A.

FIG. 10 shows the circuitry of the present technology.

FIG. 11 shows an alternative circuitry of the present technologyconnected in a flashing mode.

FIG. 12 shows an alternative circuitry of the present technology.

FIG. 13 shows an alternative circuitry of the present technology.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Except as otherwise expressly provided, the following rules ofinterpretation apply to this specification (written description, claimsand drawings): (a) all words used herein shall be construed to be ofsuch gender or number (singular or plural) as the circumstances require;(b) the singular terms “a”, “an”, and “the”, as used in thespecification and the appended claims include plural references unlessthe context clearly dictates otherwise; (c) the antecedent term “about”applied to a recited range or value denotes an approximation within thedeviation in the range or value known or expected in the art from themeasurements method; (d) the words “herein”, “hereby”, “hereof”,“hereto”, “hereinbefore”, and “hereinafter”, and words of similarimport, refer to this specification in its entirety and not to anyparticular paragraph, claim or other subdivision, unless otherwisespecified; (e) descriptive headings are for convenience only and shallnot control or affect the meaning or construction of any part of thespecification; and (f) “or” and “any” are not exclusive and “include”and “including” are not limiting. Further, The terms “comprising,”“having,” “including,” and “containing” are to be construed asopen-ended terms (i.e., meaning “including, but not limited to,”) unlessotherwise noted.

To the extent necessary to provide descriptive support, the subjectmatter and/or text of the appended claims is incorporated herein byreference in their entirety.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. Where a specific range of values isprovided, it is understood that each intervening value, to the tenth ofthe unit of the lower limit unless the context clearly dictatesotherwise, between the upper and lower limit of that range and any otherstated or intervening value in that stated range, is included therein.All smaller sub ranges are also included. The upper and lower limits ofthese smaller ranges are also included therein, subject to anyspecifically excluded limit in the stated range.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe relevant art. Although any methods and materials similar orequivalent to those described herein can also be used, the acceptablemethods and materials are now described.

All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.,“such as”) provided herein, is intended merely to better illuminate theexample embodiments and does not pose a limitation on the scope of theclaimed invention unless otherwise claimed. No language in thespecification should be construed as indicating any non-claimed elementas essential.

In the context of the present technology, body refers to any part of amammal and user similarly refers to a mammal.

A flashlight, generally referred to as 10 is shown in FIG. 1. Theflashlight 10 has the dimensions of a typical flashlight. The flashlight10 has a proximal end 12, a distal end 14 and a body 16 therebetween.The distal end 14 defines a distal aperture 18 and the proximal end 12defines a proximal aperture 20. Housed within the body 16 is an innercylinder 24 defining a first cooling channel 22 and a second coolingchannel 26 between the body 16 and the inner cylinder 24. There arecooling fins 25 in the first cooling channel 22 (See FIGS. 2B and C).Notwithstanding the size recited above, the first channel 22 has aninside diameter of about 12 mm to about 30 mm, or 15 mm to about 25 mmor about 18 mm to about 29 mm and all ranges therebetween. It is about150 mm long. As shown in FIGS. 2A, 2B and 2C, there are struts 30between the inner cylinder 24 and the body 16 to retain the innercylinder 24. FIG. 2A is an alternative embodiment that does not includethe cooling fins. The inner cylinder 24 is a heat conducting material,for example, but not limited to aluminum, copper, steel, stainlesssteel, diamond coated metal or diamond coated plastic polymer. Itfunctions as a heat sink and has a thermal conductivity of at leastabout 16 W/mK at 25° C. or about 175 W/mK at 25° C. or about 205 W/mK at25° C. or about 400 W/mK at 25° C., and all ranges therebetween. Theinner cylinder 24 is about 1.2 mm thick, to about 5 mm thick, or about 3mm thick and all ranges therebetween. The following is a list of thethermal conductivity of a number of potential materials: Stainlesssteel: Heat conduction 16 W/mK; Steel: Heat conduction 50 W/m K;Pyrolytic Graphite: Heat conduction 700-1750 W/m K, Silver: Heatconduction 400 W/m K, Copper: Heat conduction 385 W/m K, Aluminum: Heatconduction 205 W/m K and sandwiches including these and other materials.

Returning to FIG. 1 and FIGS. 2A and B, Peltier modules 40 are locatedon a plate 42 that is also a heat sink and is made of the materialslisted above or has the functional capabilities listed above. Plate 42and cylinder 24 can also be one single extrusion. The inner cylinderextrusion can also be open as in FIG. 2C, with cooling fins 25 actingalso as support against the body 48. Four Peltier modules 40 are shownin FIG. 1. The plate 42 is located in a cutout (aperture) 44 in the body16. This allows for contact with the Peltier modules 40. The body 16 mayhave at least one insulating layer 46 and one supporting layer 48, forexample, but not limited to foam and a Poly Vinyl Chloride (PVC) shell,respectively. The shell is about 32 mm OD, and about 29 mm ID, whichleaves a 1.5 mm air gap around the inner cylinder 24. The insulatinglayer 46 may be a 1.5 mm thick, rubber foam or other materials such as,but not limited to leather, fabric, or wood. The heat conductivity islow, possible less than 1 W/m/K.

Circuitry 50 is housed within the flashlight 10. The circuitry 50 has atransistor oscillator 52, with a 10:1 or 25:1 or 500:1 or preferably a100:1, and all ranges therebetween, step-up transformer 54 to providethe required voltage and an about 47 μF decoupling capacitor 56, whichmay or may not be used. Alternatively, the circuitry may be anintegrated circuit containing the transistor oscillator 52 and othercomponents needed to generate DC or a pulsed DC power may be used. Atleast one LED 58 is located at the distal end 14 and is in electricalcommunication with the circuitry 50. The LED 58 is centrally located onthe distal end 14, with or without a reflector, or, if multiple LEDs 58are employed, they form a ring around the distal aperture 18. A focusingring 60 is also located at the distal end 14.

As shown in FIG. 1, there is convective air flow 62 in both the firstchannel 22 and the second channel 26. This convective air flow 62 andthe heat sink function to provide the necessary temperature differentialacross the Peltier modules 40, as described below.

In use, a user grasps the flashlight 10 such that their hand is on thePeltier module 40, more specifically, their palm. The temperaturedifferential between the approximately 37° C. palm on the outer surface64 of the Peltier module 40 and the inner surface 66 (FIG. 2A) of thePeltier module 40 generates sufficient power to light the LED 58, whichappears from experimental results to be about a 5° C. temperature rangeor about 6.5° C. temperature range, or about a 7.5° C. temperature rangeor about a 10° C. temperature range or about a 15° C. temperature range.The device is switchless and is turned on by the user's body heat. Aswould be known to one skilled in the art, the temperature range neededcan be calculated once the parameters of the tile are known.

A flashlight 10 can include a strap 68, as shown in FIG. 1, forreleasably attaching to a user's arm. In this case, the arm wouldprovide the 37° C. surface.

FIG. 2E shows the flashlight 10 in another layout, where the distal end14 defines a distal aperture 18 which consists of several smallerapertures 62, and the proximal end 12 defines a proximal aperture 20.This allows for the inclusion of a larger reflector 59. Housed withinthe body 48 is a finned heat sink extrusion 42, which could have fins 25at any angle to the flat part of 42 touching the thermoelectricgenerators, and defining a single cooling channel 22. Body 48 is madefrom an insulating material such as plastic, or wood, or any number ofpoor heat conductive materials with heat conductivity of 0.1 and 0.3W/mK. It is shown here without the insulating layer 46.

The heat sink is made from a heat conducting material, for example, butnot limited to aluminum, copper, steel, stainless steel, diamond coatedmetal or diamond coated plastic polymer. It has a thermal conductivityof at least about 16 W/mK at 25° C. or about 175 W/mK at 25° C. or about205 W/mK at 25° C. or about 400 W/mK at 25° C., and all rangestherebetween. As shown in FIG. 2F, the extrusion heat sink fins 25 cantouch the inner body 48 for support, as do the struts 30 in FIGS. 2A and2B.

As shown in FIG. 2D, there is convective air flow 62 between severalsmaller apertures 18, the channel 22, and the distal end 20. Thisconvective air flow 62 and the heat sink function to provide thenecessary temperature differential across the Peltier modules 40, asdescribed above.

As shown in FIG. 3, in a second embodiment, a flashlight, generallyreferred to as 110 is provided. The flashlight 110 is configured almostidentically to the flashlight in FIG. 1.

The flashlight 110 has a first end 112, a second end 114 and a body 116therebetween. The first end 114 defines a first aperture 118 and thesecond end 112 defines a second aperture 120. Housed within the body 116is an inner cylinder 124 defining a first cooling channel 122 and asecond cooling channel 126 between the body 116 and the inner cylinder124. The first channel has a inside diameter of about 12 mm to about 30mm, or 15 mm to about 25 mm or about 18 mm to about 29 mm and all rangestherebetween. It is about 150 mm long. As shown in FIGS. 4A, B, thereare struts 130 between the inner cylinder 124 and the body 116 to retainthe inner cylinder 124. FIG. 4A does not include the cooling fins 125and FIGS. 4B and 4C are alternative embodiments that include the coolingfins 125. The inner cylinder extrusion can also be open as in FIG. 4C,with cooling fins 125 acting also as support against the body 148. Theinner cylinder 124 is a heat conducting material, for example, but notlimited to aluminum, steel, stainless steel, pyrolytic graphite, copper,diamond coated metal or diamond coated plastic polymer. It functions asa heat sink and has a thermal conductivity of at least about 16 W/mK at25° C. or 175 W/mK at 25° C. or about 205 W/mK at 25° C. or about 400W/mK at 25° C., and all ranges therebetween. The inner cylinder 124 isabout 2 mm thick, to about 5 mm thick, or about 3 mm thick and allranges therebetween. The following is a list of the thermal conductivityof a number of potential materials: Stainless Steel: Heat conduction 16W/m K; Steel: Heat conduction 50 W/m K, Pyrolytic Graphite: Heatconduction 700-1750 W/m K, Silver: Heat conduction 400 W/m K, Copper:Heat conduction 385 W/m K, Aluminum: Heat conduction 205 W/m K andsandwiches including these and other materials.

Returning to FIG. 3, Peltier modules 140 are located on a plate 142 thatis also a heat sink and is made of the materials listed above or has thefunctional capabilities listed above or alternatively is a heatconductive rubber or flexible plastic polymer. Four Peltier modules 140are shown in FIG. 3. The plate 142 is located in a cutout 144 in thebody 116. Plate 142 and cylinder 124 can also be one single extrusion. Aheat conductive rubber or plastic polymeric material layer 170 islocated on outer side 164 of the Peltier modules 140 for a user to presstheir head or any other suitable body part into. The body 116 has atleast one insulating layer 146 and one supporting layer 148, forexample, but not limited to foam and a Poly Vinyl Chloride (PVC) shell,respectively. The shell is about 32 mm OD, and about 29 mm ID, whichleaves a 1.5 mm air gap around the inner cylinder 124. The insulatinglayer 146 may be a 1.5 mm thick, rubber foam or other materials such as,but not limited to leather, fabric, or wood. The heat conductivity islow, possible less than 1 W/m/K.

Circuitry 150 is housed within the headlamp 110. The circuitry 150 has atransistor oscillator 152, with a 10:1 or 25:1 or 500:1 or preferably a100:1, and all ranges therebetween step-up transformer 154 to providethe required voltage and an about 47 μF decoupling capacitor 156, whichmay or may not be used. Alternatively, the circuitry may be anintegrated circuit containing the transistor oscillator 152 and othercomponents needed to generate DC or a pulsed DC power may be used. Atleast one LED 158 is in electrical communication with the circuitry 150.The LED or LEDs 158 can be oriented at any angle from the circuitryenclosure.

As shown in FIG. 3, there is convective air flow 162 in both the firstchannel 122 and the second channel 126. This convective air flow 162 andthe heat sink function to provide the necessary temperature differentialacross the Peltier modules 140, as described above.

An alternative design of the flashlight for mounting on the head isshown in FIGS. 5A, B and 5C. The headlamp 210 has a half cylinder 224with a first end 212, a second end 214, and a cooling channel 226therebetween. The first end 214 defines a first aperture 218 and thesecond end 212 defines a second aperture 220. The half cylinder 224 hasa inside diameter of about 12 mm to about 30 mm, or 15 mm to about 25 mmor about 18 mm to about 29 mm and all ranges therebetween. It is about50 mm long. Plate 214 and cylinder 224 can also be one single extrusion.The cooling channel 226 has a series of cooling fins 225 therein. Thehalf cylinder 224 is a heat conducting material, for example, but notlimited to aluminum, pyrolytic graphite, copper, steel, stainless steel,diamond coated metal or diamond coated plastic polymer. It functions asa heat sink and has a thermal conductivity of at least about 16 W/mK at25° C. or 175 W/mK at 25° C. or about 205 W/mK at 25° C. or about 400W/mK at 25° C., and all ranges therebetween. The half cylinder 224 isabout 1.5 mm thick, to about 5 mm thick, or about 3 mm thick and allranges therebetween. The following is a list of the thermal conductivityof a number of potential materials: Stainless Steel: 16 W/K; Steel: Heatconduction 50 W/m K, Pyrolytic Graphite: Heat conduction 700-1750 W/m K,Silver: Heat conduction 400 W/m K, Copper: Heat conduction 385 W/m K,Aluminum: Heat conduction 205 W/m K and sandwiches including these andother materials.

Peltier modules 240 are located on the half cylinder 224 and a layer 270of a heat conductive rubber or flexible plastic polymer may be on theouter side 264 of the Peltier modules 240 to facilitate thermal contactwith the irregular shape of the head.

Circuitry 250 is housed within the headlamp 210. The circuitry 250 has atransistor oscillator 252, with a 10:1 or 25:1 or 500:1 or preferably a100:1, and all ranges therebetween step-up transformer 254 to providethe required voltage and an about 47 μF decoupling capacitor 256, whichmay or may not be used. Alternatively, the circuitry may be anintegrated circuit containing the transistor oscillator 252 and othercomponents needed to generate DC or a pulsed DC power may be used. Atleast one LED 258 is located in the vicinity of the midline 259 of thehalf cylinder 224 and is in electrical communication with the circuitry250. If multiple LEDs 258 are employed, they are centrally located inthe vicinity of the midline 259. A strap 268 is attached to each end212, 214 of the half cylinder 224. As shown in FIGS. 5A and C, apertures272 along a front side 274 allow for further air flow. As shown in FIGS.5A and C, the back 276 has a foam layer 246 on the surface not coveredwith the Peltier modules 240. As shown in FIG. 5C, a gooseneck 278extends from the front 274 of the half cylinder 224 to allow the LED 258to be positioned.

As shown in FIG. 5A, there is convective air flow 262 in the halfcylinder 224. This convective air flow 262 and the heat sink function toprovide the necessary temperature differential across the Peltiermodules 240, as described above.

In yet another embodiment, a keychain flashlight 310 is provided, asshown in FIGS. 6A and B. The keychain flashlight 310 is about 55 mmlong, by about 20 mm wide, by about 7 mm thick. The flashlight 310 has aproximal end 312, a distal end 314 and a body 316 therebetween. Thedistal end 314 defines a distal aperture 318 and the proximal end 312defines a proximal aperture 320. Housed within the body 316 is acylinder 324 defining a cooling channel 322. The cylinder 324 is a heatconducting material, for example, but not limited to aluminum, copper,steel, stainless steel, diamond coated metal or diamond coated plasticpolymer. It functions as a heat sink and has a thermal conductivity ofat least about 16 W/mK at 25° C. or 175 W/mK at 25° C. or about 205 W/mKat 25° C. or about 400 W/mK at 25° C., and all ranges therebetween. Thefollowing is a list of the thermal conductivity of a number of potentialmaterials: Stainless Steel: 16 W/K; Steel: Heat conduction 50 W/m K,Pyrolytic Graphite: Heat conduction 700-1750 W/m K, Silver: Heatconduction 400 W/m K, Copper: Heat conduction 385 W/m K, Aluminum: Heatconduction 205 W/m K and sandwiches including these and other materials.

Peltier modules 340 are located on a first side 376 in a cutout 344 inthe body 316. The body 316 has at least one insulating layer 346 on thefirst side 376 of the keychain 310, and another on a second side 377.The insulating layer 346 may be a 1.5 mm thick, rubber foam or othermaterials such as, but not limited to leather, fabric, or wood. Thelayer may be perforated to allow for better cooling. The heatconductivity is low, possible less than 1 W/m/K.

Circuitry 350 is housed within the keychain 310. The circuitry 350 has atransistor oscillator 352, with a 10:1 or 25:1 or 500:1 or preferably a100:1, and all ranges therebetween step-up transformer 354 to providethe required voltage and an about 47 μF decoupling capacitor 356, whichmay or may not be used. Alternatively, the circuitry may be anintegrated circuit containing the transistor oscillator 352 and othercomponents needed to generate DC or a pulsed DC power may be used. Atleast one LED 358 is located at the distal end 314 and is in electricalcommunication with the circuitry 350. The LED 358 is centrally locatedon the distal end 314, or, if multiple LEDs 358 are employed, they forma ring around the distal aperture 318. A keychain 380 is attached to akeychain aperture 382 in the proximal end 312.

As shown in FIGS. 6A and 6B, there is convective air flow 362 in thechannel 322. Additional apertures 372 along at least a second side 374allow for further air flow. This convective air flow 362 and the heatsink function to provide the necessary temperature differential acrossthe Peltier modules 340, as described above.

Whether a headlamp, keychain or flashlight, in another embodiment, theinner cylinder is replaced with a solid or perforated heat sink 424, asshown in FIGS. 7A and B, which may be round, oval, square, flattened orany suitable cross section. There is one cooling channel 26 between thebody 16 and the solid or perforated heat sink 424 on both sides of theheadlamp or flashlight, which may be perforated to allow for cooling.

An alternative embodiment of the flashlight of FIGS. 1-2 is shown inFIGS. 8A, 8B, 8C and 8D. The flashlight, generally referred to as 510,has the dimensions of a typical flashlight. The flashlight 510 has aproximal end 512, a distal end 514 and a body 516 therebetween. Thedistal end 514 defines a distal aperture 518 and the proximal end 512defines a proximal aperture 520. Housed within the body 516 is an innercylinder 524 defining a first cooling channel 522 and a second coolingchannel 526 between the body 516 and the inner cylinder 524. There arecooling fins 525 in the first cooling channel 522 (See FIGS. 8C and D).Plate 542 and cylinder 524 can also be one single extrusion.Notwithstanding the size recited above, the first channel 522 has aninside diameter 570 of about 12 mm to about 30 mm, or 15 mm to about 25mm or about 18 mm to about 29 mm and all ranges therebetween. It isabout 150 mm long. As shown in FIGS. 8B and 8C, there are struts 530between the inner cylinder 524 and the body 516 to retain the innercylinder 524. The inner cylinder extrusion can also be open as in FIG.8C, with cooling fins 525 acting also as support against the body 548.FIG. 8B is an alternative embodiment that does not include the coolingfins. The inner cylinder 524 is a heat conducting material, for example,but not limited to aluminum, copper, steel, stainless steel, diamondcoated metal or diamond coated plastic polymer. It functions as a heatsink and has a thermal conductivity of at least about 16 W/mK at 25° C.or about 175 W/mK at 25° C. or about 205 W/mK at 25° C. or about 400W/mK at 25° C., and all ranges therebetween. The inner cylinder 524 isabout 1.5 mm thick, to about 10 mm thick, or about 7 mm thick and allranges therebetween. The following is a list of the thermal conductivityof a number of potential materials: Stainless Steel: Heat conduction 16W/m K; Steel: Heat conduction 50 W/m K; Pyrolytic Graphite: Heatconduction 700-1750 W/m K, Silver: Heat conduction 400 W/m K, Copper:Heat conduction 385 W/m K, Aluminum: Heat conduction 205 W/m K andsandwiches including these and other materials.

Returning to FIGS. 8A, 8B and 8C, Peltier modules 540 are located on aplate 542 that is also a heat sink and is made of the materials listedabove or has the functional capabilities listed above. One, two, threefour or more Peltier modules 540 are shown in FIG. 1. The plate 542 islocated in a cutout 544 in the body 516. The body 516 may have at leastone insulating layer 546 and one supporting layer 548, for example, butnot limited to foam and a Poly Vinyl Chloride (PVC) shell, respectively.The shell is about 32 mm OD, and about 29 mm ID, which leaves a 1.5 mmair gap around the inner cylinder 524. The insulating layer 546 may be a1.5 mm thick, rubber foam or other materials such as, but not limited toleather, fabric, or wood. The heat conductivity is low, possible lessthan 1 W/m/K.

Circuitry 550 is housed within the flashlight 510. The circuitry 550 hasa transistor oscillator 552, with a 10:1 or 25:1 or 500:1 or preferablya 100:1, and all ranges therebetween step-up transformer 554 to providethe required voltage and an about 47 μF decoupling capacitor 556, whichmay or may not be used. Alternatively, the circuitry may be anintegrated circuit containing the transistor oscillator 552 and othercomponents needed to generate DC or a pulsed DC power may be used. Atleast one LED 558 is located at the distal end 514 and is in electricalcommunication with the circuitry 550. The LED 558 is centrally locatedon the distal end 514, or, if multiple LEDs 558 are employed, they forma ring around the distal aperture 518, and can be seated in a reflector559 as also show in FIG. 9A.

As shown in FIG. 8A, there is convective air flow 562 in both the firstchannel 522 and the second channel 526 which vents through largeapertures 583 and small apertures 581 as seen in FIG. 9A. Thisconvective air flow 562 and the heat sink function to provide thenecessary temperature differential across the Peltier modules 540, asdescribed below.

The flashlight 510 can include a strap 568, as shown in FIG. 1, forreleasably attaching to a user's arm. In this case, the arm wouldprovide the 37° C. surface.

The flashlight 510 has a ring 572 of heat conducting material, forexample, but not limited to aluminum, copper, steel, stainless steel,diamond coated metal or diamond coated plastic polymer, which in thepreferred embodiment is a grooved aluminum head 572. There is a groovedaluminum tail 574. Both physically attached to the inner tube 524.Without being bound to theory, this allows for further heat sinking.

An electronic circuit may have a three position switch 576 that allows auser to select whether the LED 558 is to be powered from the Peltiermodule 540, or from a storage capacitor 582, which can be, for example,but not limited to a battery or a supercapacitor. A flexible solar cell580 is located on the aluminum head 572, on plate 542 or tail 574. Asolid solar cell can be located on the plate 542, and is in electricalcommunication with the storage capacitor 582 and the LED 558.

In use, a user grasps the flashlight 510 such that their hand is on thePeltier module 540, more specifically, their palm. The temperaturedifferential between the approximately 37° C. palm on the outer surface564 of the Peltier module 540 and the inner surface 566 (FIG. 8B) of thePeltier module 540 generates sufficient power to light the LED 558,which appears from experimental results to be at least about 2 to about5° C., with larger temperature differential providing more power andtherefore a brighter light, for example, but not limited to, about 3° C.temperature range, or about a 6° C. temperature range or about a 10° C.temperature range or about a 12° C. temperature range or about a 14° C.temperature range. As would be known to one skilled in the art, thetemperature range needed can be calculated once the parameters of thetile are known.

FIGS. 9A, 9B and 9C shows another alternative embodiment of the headlamp, generally referred to as 610. The headlamp 610 has a rectangularbody 624 with a first end 612, with a first port 613 a second end 614,with a second port 615 and a cooling channel 626 therebetween. Bridges627 extend across a part of the cooling channel 626 so as to not impedemovement of air in the cooling channel 626. This improves heatconduction and cooling. The rectangular body 624 has a width of about 6mm to about 30 mm, or 15 mm to about 25 mm or about 18 mm to about 29 mmand all ranges therebetween. It is about 150 mm long. A front side 641has a series of cooling fins 625 thereon. The rectangular body 624 is aheat conducting material, for example, but not limited to aluminum,steel, stainless steel, pyrolytic graphite, copper, diamond coated metalor diamond coated plastic polymer. It functions as a heat sink and has athermal conductivity of at least about 16 W/mK at 25° C. or 175 W/mK at25° C. or about 205 W/mK at 25° C. or about 400 W/mK at 25° C., and allranges therebetween. The body 624 is about 1 mm thick, to about 5 mmthick, or about 2 mm thick or about 3 mm thick and all rangestherebetween. The following is a list of the thermal conductivity of anumber of potential materials: Stainless steel: Heat conduction 16 W/mK; Steel: Heat conduction 50 W/m K, Pyrolytic Graphite: Heat conduction700-1750 W/m K, Silver: Heat conduction 400 W/m K, Copper: Heatconduction 385 W/m K, Aluminum: Heat conduction 205 W/m K and sandwichesincluding these and other materials.

Peltier modules 640 are located on the body 624 and a layer 670 of aheat conductive rubber or flexible plastic polymer may be on the outerside 664 of the Peltier modules 640.

Circuitry 650 is housed within the headlamp 610. The circuitry 650 has atransistor oscillator 652, with a 100:1 step-up transformer 654 toprovide the required voltage and a 47 μF decoupling capacitor 656, whichmay or may not be used. At least one LED 658 is located in the vicinityof the midline 659 of the body 624 and is in electrical communicationwith the circuitry 650. A current limiting resistor 680 is in serieswith the LED. If multiple LEDs 658 are employed, they are centrallylocated in the vicinity of the midline 659. A strap 668 is attached toeach end 612, 614 of the body 624. As shown in FIG. 9C, a gooseneck 678extends from the front 274 of the body 624 to allow the LED 658 to bepositioned.

As shown in FIG. 9A, there is convective air flow 662 in the body 624.This convective air flow 662 and the heat sink function to provide thenecessary temperature differential across the Peltier modules 640, asdescribed above.

An electronic circuit has a three position switch 676 that allows a userto select whether the LED 658 is to be powered from the Peltier module640, or from a storage capacitor 682, which can be, for example, but notlimited to a battery or a supercapacitor. The third switch position isset for charging only. A solar cell 680 is located on the cooling fin618 and is in electrical communication with the storage capacitor 682and the LED 658. The switch can be replaced by a suitable electroniccircuit and a single button switch to switch between the three modes.

FIGS. 10 through 13 show the circuitry for the above embodiments.

Development of the Light Source

Example 1

In order to determine the feasibility of using heat from the hand of auser to power a flashlight, calculations had to be performed. An averagehuman dissipates around 350,000 Joules per hour, or 97 watts. Theaverage surface area of the human skin is 1.7 m² or 17,000 cm², so theheat dissipation equals to (97/17000)*1000=5.7 mW/cm². A useful area ofthe palm is about 10 cm². This implies that 57 mW could be available.The thermal efficiency of a Peltier module is cited at about 6%, hencethe palm of the hand may be able to generate 3.4 mW. At least 25microwatts is needed to light an LED and about 100 microwatts is neededto obtain usable LED brightness.

Example 2

The voltage and power generated by Peltier modules was determined. Tile1 had an area of 1.36 cm² and an internal resistance of 5 ohms, and tile2 was 4 cm² and had an internal resistance of 2.4 ohms. The tiles wereheated on a first side and cooled on a second side, using a temperaturedifference ranging from about 1° C. to about 15° C. Table 1 shows theresults for about a 5° C. differential and about a 10° C. differential.

The results show that both Peltier modules produced enough power throughthe power conversion circuit of the flashlight, to light an LEDadequately, at between approximately 50 mV and about 100 mV.

Example 3

As about 2500 mV is needed to light an LED, the voltage needed to beincreased. A power converter integrated circuit (LTC3108 from LinearTechnology™) was used as a three pin, very low transistor oscillator,with a 100:1 step-up transformer to provide the required voltage. Thesetwo components were coupled to a 47 μF capacitor to provide a circuit,which in turn was coupled to the LED. This provided good LED brightnesswith less than 50 mV DC input across the oscillator. The efficiency ofthe converter was about 10% at 50 mV. Using 5 mm, 15 degree LEDs, twosystems were tested, as shown in Table 2. The step-up transformer can beabout 100:1 or between about 25:1 and 500:1 and all ranges therebetween.The capacitor can be about 47 μF, or about 10 μF to about 100 μF toabout 1000 μF or about 1 μF to about 1000 μF, and all rangestherebetween.

When the power from the Peltier module is converted to alternatingcurrent by the oscillator, and then back to over 3 to 6 volts of directcurrent and stored in a supercapacitor or a secondary cell, the LED canthen be switched so it is powered either directly from the LED or fromthe storage. The charge stored in a typical 1 Farad supercapacitor canpower an LED for over 60 minutes and provide higher brightness that ifpowered directly from the Peltier module.

Measurements made at room temperature of 21° C. with a Tondai LX 1010E3Digital Lux meter at a distance of 1 foot (30 cm) between the source andthe meter, are shown in Table 3.

Advantages of the exemplary embodiments described herein may be realizedand attained by means of the instrumentalities and combinationsparticularly pointed out in this written description. It is to beunderstood that the foregoing general description and the followingdetailed description are exemplary and explanatory only and are notrestrictive of the claims below. While example embodiments have beendescribed in detail, the foregoing description is in all aspectsillustrative and not restrictive. It is understood that numerous othermodifications and variations can be devised without departing from thescope of the example embodiment.

TABLE 1 Voltage for 5° C. Power for Voltage for Power for a Peltier Temp5° C. Temp 10° C. Temp 10° C. Temp Module & Difference DifferenceDifference Difference Size (mV) (mW/cm²) (mV) (mW/cm²⁾ Tile 1 50.3 0.3894.6 mV 1.35 (smaller) Tile 2 50.3 0.26 73.7 mV 0.56 (larger)

TABLE 2 Theoretical Power Conv. Actual Power Tile area Hand heat palmpower Tile Efficiency Effic. at 10° C. at LED Flashlight (cm²) (mW/cm²)(mW) (Estimate %) TΔ (%) (mW) F 1 5.4 × 5.7 = 30.8 10 10 0.7 F 2 16 ×5.7 = 91   10 10 0.45

TABLE 3 LED Brightness at 10° C. TΔ Flashlight (Lux) F1 8 F2 11

While example embodiments have been described in connection with what ispresently considered to be an example of a possible most practicaland/or suitable embodiment, it is to be understood that the descriptionsare not to be limited to the disclosed embodiments, but on the contrary,is intended to cover various modifications and equivalent arrangementsincluded within the spirit and scope of the example embodiment. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, many equivalents to the specific exampleembodiments specifically described herein. Such equivalents are intendedto be encompassed in the scope of the claims, if appended hereto orsubsequently filed. For example, the system described herein could beused to power any portable device that has a power sink with anequivalent or lower power requirement. While four Peltier modules wereused, as few as one and more than four could similarly be employed. Theouter shell may be any suitable elongate shape, for example, but notlimited to, square, oblong, round, or octagonal in cross section.

What is claimed is:
 1. A portable, thermoelectrically powered device,the device comprising: an at least one thermoelectric generator forextracting body heat from a user; an outer shell; a heat sink in contactwith an inner surface of the thermoelectric generator, the heat sinkconfigured to provide an elongated first cooling channel therethroughterminating at a first end and a second end with an at least one heatsink first aperture and an least one heat sink second aperture; andcircuitry in electrical communication with the thermoelectric generator,the circuitry comprising a transistor oscillator, a step-up transformerand a decoupling capacitor, the circuitry in electrical communicationwith a power sink, such that in use, a temperature gradient across thethermoelectric generator is sufficient to result in generation of atleast 25 microwatts of power.
 2. The portable thermoelectrically powereddevice of claim 1, wherein the step-up transformer is further defined asan about 25:1 to about a 500:1 step-up transformer.
 3. The portablethermoelectrically powered device of claim 1, wherein the heat sink hasa thermal conductivity of at least about 16 W/mK at 25° C.
 4. Theportable thermoelectrically powered device of claim 1, the devicecomprises the outer shell, the outer shell having a first end and asecond end and a bore therebetween, the first end defining an at leastone aperture and the second end defining an at least one aperture andfurther comprises an insulating layer adjacent the outer shell.
 5. Theportable thermoelectrically powered device of claim 1, wherein the heatsink is an aluminum, copper, steel, stainless steel or pyrolyticgraphite or a diamond coated substrate.
 6. The portablethermoelectrically powered device of claim 1, further comprising asecond cooling channel between the heat sink and the outer shell andstruts for supporting an inner cylinder in the outer shell.
 7. Theportable thermoelectrically powered device of claim 1, wherein the powersink is at least one LED and the device is a light source.
 8. Theportable thermoelectrically powered device of claim 7, wherein the lightsource is a head lamp or a flashlight.
 9. The portablethermoelectrically powered device of claim 8, wherein the light sourceis a flashlight.
 10. The portable thermoelectrically powered device ofclaim 1, wherein the decoupling capacitor is about 47 μF or more.
 11. Athermoelectrically powered light, the light comprising: at least onethermoelectric generator for extracting body heat from a user; a firstend and a second end, the first end and second end defining an at leastone first aperture and an at least one second aperture, respectively; aheat sink in contact with an inner surface of the thermoelectricgenerator and defining an elongated first cooling channel; and circuitryin electrical communication with the thermoelectric generator, thecircuitry comprising a transistor oscillator, a step-up transformer anda decoupling capacitor, the circuitry in electrical communication withan at least one light emitting diode (LED).
 12. The thermoelectricallypowered light of claim 11, further comprising a body including aninsulating layer and a supporting layer and defining a bore extendingbetween the at least one first and at least one second apertures; thethermoelectric generator located on and extending through the body andthe heat sink housed in the bore.
 13. The thermoelectrically poweredlight of claim 11, wherein the heat sink has a thermal conductivity ofat least about 175 W/mK at 25° C.
 14. The thermoelectrically poweredlight of claim 11, wherein the heat sink is an aluminum, copper,pyrolytic graphite or diamond coated inner cylinder.
 15. Thethermoelectrically powered light of claim 11, further comprising asecond cooling channel between the heat sink and the body, and strutsfor supporting the heat sink in the body.
 16. The thermoelectricallypowered light of claim 11, wherein the step-up transformer is furtherdefined as an about 25:1 to about a 500:1 step-up transformer.
 17. Thethermoelectrically powered light of claim 11, wherein the decouplingcapacitor is an about 47 μF or more.
 18. The thermoelectrically poweredlight of claim 11, wherein the light is a headlamp or a flashlight. 19.A method of providing light, the method comprising: a user holding orpressing a thermoelectrically powered flashlight or body lamp againsttheir body such that the body contacts at least one thermoelectricgenerator of the flashlight or body light, the flashlight or body lampcomprising: the at least one thermoelectric generator; a heat sink incontact with an inner surface of the thermoelectric generator; andcircuitry in electrical communication with the thermoelectric generator,the circuitry comprising a transistor oscillator, a step-up transformerand a decoupling capacitor, the circuitry in electrical communicationwith an at least one LED; the thermoelectric generator extracting bodyheat from the user; the heat sink removing body heat from thethermoelectric generator; the thermoelectric generator producing heatenergy; and the circuitry communicating an electric current to at leastone LED, thereby providing a steady or a flashing light.
 20. The methodof claim 19, further comprising storing the heat energy as a charge in acapacitor or battery of the flashlight or body light.